Question

Two resistances of 20ohm and 30ohm are connected across the the gaps of a metre bridge. The bridge wire has diameter 0.5mm and resistance of 2ohm. the emf of cell is 2V Assume that the internal resistance of the cell is zero. Calculate the resistivity of the material of bridge wire and the current provided by the cell when the bridge is balancedTwo resistances of 20ohm and 30ohm are connected across the the gaps of a metre bridge. The bridge wire has diameter 0.5mm and resistance of 2ohm. the emf of cell is 2V Assume that the internal resistance of the cell is zero. Calculate the resistivity of the material of bridge wire and the current provided by the cell when the bridge is balancedl

Answer 1

Answer:

Explanation:

12th

>Physics

>Current Electricity

>Electrical Resistance & Resistivity

>A wire is 1.0 m long , 0.2 ...

Physics

A wire is 1.0 m long , 0.2 mm in diameter and has a resistance of 10 Ω. Calculate the resistivity of its material.

Medium

Answer

Given,

l=0.1m=1000mm

d=0.2mm∴radius(r)=  

2

0.2

​

=0.1mm

R=10Ω

To find,

Resistivity(ρ)

ρ=R  

l

A

​

 

where,

R= Resistance

l= Length of wire

A= Cross sectional area of wire

Cross sectional area of cylinder (A)=Πr  

2

 

⇒A=π×(0.1)  

2

 

⇒A=0.0314mm  

2

 

∴ρ=10(  

1000

0.0341

​

)

⇒ρ=0.000314Ω−mm

⇒ρ≃3.14×10  

−7

Ω−m

So, the resistivity of the material is equal to 3.14×10  

−